Welding machine



June 30, 1942. PURAT 2,287,945

WELDING MACHINE Filed March 6, 1940 6 Sheets-Sheet l 6 Sheets-Sheet 2 H. PURAT WELDING MACHINE [HUI Filed March 6, 1940 June 30,1942.

. mlxll June 30, 1942. H, PURAT 2,287,945

WELDING MACHINE Filed March 6, 1940 6 Sheets-Sheet 5 J5 I W 76 I '79 2 ex 2 55% 57 61 g 22 as 55 45 so 20 54 1x- I r In; 51 aim r-- 1 155 159160 ll 1 Z9 June 30, 1942. H. PuRAT 2,287,945

WELDING MACHINE Filed March 6, 1940 6 Sheets-Sheet 5 9 El r 7 1 o 121 89 r 2 I Z l r-"" 1 11'! 96 1' 11 I 116 I I I I r "0 I E9 in I Z Z I l l 122 '80 I 101 Z -.9 I

% //////l l l! g 91 8 85 June 30, 1942. H, mm 2,287,945

WELDING- MACHINE Filed March a, 1940 e Sheets- Sheet e Patented June 30, 1942 WELDING moms Hugo Purat, Detroit, Mich., asaignor to Progressive Welder Company, Detroit, Mich., a corporation of Michigan Application March 6, 1940, Serial No. 322,567

8 Claims.

My invention has for its object to provide a plurality of welder electrodes in welding machines, and wherein the electrodes may be cushioningly. mounted, with reference to their engagement with the work, and maintained in contact with the work, during a welding cycle of the machine, to hold the work. Thus, the welder electrodes may be, simultaneously, moved to and engage the work by the electrodes to secure and retain the parts of the work in suitable welding relation to eliminate various forms of clamping devices, and, also, prevent mushrooming the ends of the electrodes by striking the mark. I

My invention, also, contemplates means, whereby'a group of welder electrodes may be positioned along a work surface and the'eifective pressure of their engagement thereagainst modified, individually, to afford a requisite degree of pressure on the work. Each electrode may, also, be manipulated and its relation to the pressure may be varied to produce its individual pressure on the work and accommodate areas having increased metal thickness or resiliency or spread between parts of the work, while maintaining a desirable degree resiliency of pressure exerted by the electrodes.

My invention, also, has for an object to provide a suitable switch element for completing the circuit of the welding current to each electrode or set of electrodes. The electrodes and the switches may, thus, be connected by short, electric, flexible conductors and eliminate a plurality of long, flexible conductors, commonly used to connect a plurality of electrodes with a source of welding current.

My invention has for a further object to provide a means for controlling the sequential operations of a plurality of welder electrodes within a welding cycle. Variations may be made, selectively, to produce the required duration of the flow of the welding current, the necessary potential, and the repetitive completion of the circuit through each welder, where required. The parts of the construction, embodying my invention, are so formed that they may be, electrically or pneumatically, operated to produce efflcient welding operations in a, minimum period of time.

The invention consists in other features, which will appear from the following description and upon examination of the drawings forming a part hereof. Structures contalning the invention may partake of diflerent, forms and may be varied in their details and still embody the invention. To

1 the claims.

illustrate a practical application of the lnven- 5 tion, I have selected a welding machine as an example of the various structures containing the invention, and shall describe the selected welding machine hereinafter, it being understood that certain features of my invention may be used to advantage without a corresponding use of other features of the invention, and without departing from the spirit of the invention, as presented in The particular structure selected is shown in the accompanying drawings.

Fig. 1 of the drawings illustrates a front elevational view of a welding machine structure containing the features of my invention. Fig. 2 illustrates a transverse sectional view of the machine, as taken on the plane of the broken line 2-2, indicated in Fig. 1. Fig. 3 illustrates a cross-sectional view, taken through one of the welding units, comprising a pressure switch and a welding electrode. Fig. 4 illustrates a crosssectional view of a multiple pneumatically-operated valve. Fig. 5 is a view of a section, taken on the plane of the line 55, indicated in Fig. 1, of one of the adjustable control valves. Fig. 6 is a view of a section taken on the plane of the line 66, indicated in Fig. 5. Fig. 7 is a view of a section of the pneumatically-operated valve, taken on the plane of the line 1-1, indicated in Fig. 4. Fig. 8 illustrates a top view of one of the electrical switches of the machine. Fig. 9 is a view of a section taken on the plane of the line 9-9, indicated in Fig. 1, and illustrates a mechanical means for producing, distribution of the electrical and pneumatic energy utilized by various elements of the machine. Fig. 10 is a top plan view, a part thereof being in cross-section, to show certain of the details of the mechanical means, shown in part in Fig. 9. Fig. 11 illustrates, diagrammatically, the electrical and pneumatic connections between the parts of the machine and their controlling means.

The welding machine shown in the drawings, for the purpose of illustration, has a supporting frame It, on which is mounted a pair of cylinders I I. Electrodes I! are mounted on a movable frame 20, which is caused to move by the pressure in the cylinders l5, that actuate pistons located in the cylinders and connected by the piston rods 2 I to the frame 20. Upon manipulation of suitable valves, the cylinders l5 may be connected to a source of supply of air under pressure, and themovable frame 20 and electrodes l8 will be moved, to engage the work.

The parts of the work, which are to be welded together, are located on the electrodes 22, which may be secured in a bar 24. The bar 24 is insuconductor 26, to one side of the secondary 21 of the welding transformer 28 (Fig. 11) Since the welder electrodes it, simultaneously, approach and contact the work, upon movementof the frame 20, they act to press parts of the work against the electrodes 22 and afford an effective holding means for maintaining the work in position. I

In order to compensate for any variance of pressure throughout the length of the work, each of the welder electrodes I8 is caused to resiliently engage the surface of the work. As shown, particularly in Fig. 3 of the drawings, each of the electrodes I8 is secured in a block 29, which is insulatingly attached to the end of a rod 30, by an insulating sleeve 3|. The rods 30 are slidably supported in a U-bar 35, which is carried by the movable frame 26. Each rod and electrode are restricted in their movement by a pair of threaded sleeves 32 and 34, located in the sides of a U-shaped bar 35, which is connected to the length of the conductor.

movable frame 20. Intermediate the sleeves is a spring 31, which adiustably engages a ring 38, which shoulders on the rod 30 to bias the movement of the rod in one direction. The spring 31 is contained within a pair of telescoping shells 40, one of the shells bearing against an end of the sleeve 32, while the other sleeve is pressed against the ring 38, which engages a shoulder on the rod 30 formed by an enlarged portion 4| and located within the sleeve 34. Thus, rotation of the sleeve 32, in either direction, will modify the resistance of the spring 31. The sleeve 34, which v is mounted in one side of the U-bar 35, defines the limit of the downward movement of the rod 30, as urged by the spring 31, and the extent of its reactant effect upon the pressure applied or sustained by the electrode l3. Thus, when it is found expedient to alter the cushioning effect of the spring 31, or when the electrode 18 does not, securely, contact the work, the sleeve 34 may be rotated to, properly, locate the electrode l8 with reference to the'work. Also, the sleeve 32 may be rotated to modify the tension of the spring 31, to produce a desired pressure on the work. The relationship of the rod 30, with reference to either of the sleeves 32 or 34, may be moderately altered and minute adjustments may be made by lock nuts 42, threaded onto the end of the rod 3|! and bearing against the sleeve 32. Preferably, the sleeve 34 is, also, engaged by a set screw 44. The enlarged portion 4| of the rod 30 is provided with a channel 43 for receiving a tongue'of a lock washer 45. The set screw is located ina fiange of the U-bar 35 to .prevent loosening, or rotation, of the threaded sleeve 34,- w en a' desired setting has once been obtained. If desired, one of the shells 40 may be provided with suitable indicating lines, or legends, or both, to afford ready observation of the effective reactability of the spring contained within the telescoping shells, for the purpose of adjustment of the spring.

The electrodes It! may be positioned as will most advantageously attain their contact with the work. When it is necessary to dispose them' in planes at various angles to the vertical to properly engage bent portions of the work, the

U-bar 35 may be, accordingly, shaped, to present the electrodes at, substantially, a right angle to the surface of the work.

In order to, conveniently, complete the circuit of the transformer secondary through the electrodes It, the electrodes are each connected, through the block -29, to a pressure-actuated switch '48, by a short, flexible conductor 50. The conductors, thus, may be of a substantially uniform, short length and all parts of each conductor may be well spaced from the contiguous conductors, so that the electrical conductivity is not impaired by differences in the conductor lengths, as might be the result where considerable distance is found requisite between certain of the electrodes and their associated switches, and the same voltage may be used to produce the same current at the electrodes.

In the. form of construction shown in the drawings, the mobility of the switches enables adjusted movement of the switch, relative to its associated electrode, within the limitations of the To enable location of the switch, adjacent the movable electrode l8, a secondary terminal bar 55 is secured to, and insulated from, the movable frame 20, proximate to the U-shaped bar 35, and is designed to have a suitable dimension for placement of the switches along its surface and within the desired vicinity of their related electrodes Hi.

The short, flexible conductor 50 (Fig. 3) may be readily connected to a .block 51, which is secured to the casing 58 of the switch, by a bolt:

plates 62 and suitable sleeves, through which the connecting bolts extend. The blocks 61 are mounted on and secured to the terminal bar 55. The transformer secondary 21 is connected to the bar 53 and the conductor 64 connects the bars 53 and 55, If desired-a plurality of conductors 64 may be used to reduce the resistance in the secondary circuit. The conductors 64 (Fig. 2) have a length to allow for travel of the carrier frame within desirable limits. The circuit of the secondary 21 is, thus, through the conductor 23, the bar' 24, the electrodes 22 and It, the conductor 50, the switches 43, and, upon operation of each of the switches, the current flows through the terminal bar 55, the conductors 64, the bar 53, and conductor 66.

A pneumatically-actuated piston 51 is reciprocably mounted'in the cylindrical bore 68 of the casing 58. The bore 68 has two diametric dimensions to accommodate the body portion 10 and head 1| of the piston, and a spring 12 is positioned between the head 1| and the shoulder 14 formed in the wall .of the shell 58. The spring 12 acts to return the piston 81, upon the release of the pneumatic pressure. Preferably, the body portion 10 of the piston is formed of two parts, interconnected by a bolt 15'and having their proximate surfaces located in a plane inclined to the axis of the piston. To sustain the two portions of the piston in spaced relation, as against undesirable play or tight engagement, between the' angularly disposed surfaces, the drilled hole, into which the bolt 15 is threaded, is located in the part 16 of the piston and the opening, in which the shank of the bolt is'lo- 'cated, is larger than the shank and is located in the part 18. When the piston 61 is urged toward the secondary terminal block 6 I the two parts of the piston move in unison until the part 16 contacts the surface of the block, whereupon continued pressure on the part 18 causes axial displacement of the part 18, relative to the part 15 of the piston by reason of their angularly disposed faces, and the part 13 will be, wedgingly,

forced, not only against the secondary terminal block 6|, but, also, against; the wall of the casing 58. The circuit of the secondary, 21 will, thereupon, be completed through the switch 48, the conductor 50, and the electrode I8 to the work to effect the weld. The parts I6 and I8, of the piston 81, may, also, have relieved surfaces I9 formed thereon. The surfaces I9 are, diametrically, opposite each other and will, when the part I6 contacts the block 8|, allow a short sliding movement to maintain a clean surface contact between the bottom of the lower piston part and the terminal block.

As illustrated in the drawings, the switches 48 are sequentially, actuated by a pneumatic distributing element that, also, establishes, mechanically, a predetermined time period for completing the secondary circuit of the transformer 28, during the interval of each switch actuation, to produce the weld. Provision may, also, be made for modifying the intervals of switch actuation, or the time period of each weld, and the potential of the secondary circuit of each weld, according to the character of the weld to be produced or the thickness or character of the metal being worked upon. The switches 48 are connected by suitable pipe conduits to a distributor casing 80.

The casing 80 is mounted on the carrier frame 20. The casing 80 is provided with an annulus 8|, having passageways 82 located in equidistantly spaced relation to each other. The passageways 82 communicate with tapped openings, to which threaded connection of the conduits 84 may be made. The passageways are, sequentially, connected to a source of supply of pneumatic pressure, by means of a rotor 85. (Fig. 9.)

The rotor is located within the casing 80 and is suitably drilled to provide two ports 83, which register with the diametrically opposite passageways 82 and are connected, by a diametrically extending passageway 81 formed in the rotor, with the bored stem 88 of the rotor. A conventional form of swivel joint 89 may be utilized for attaching the stem to the source of supply of pneumatic pressure. The rotor 85 is operated through a train of gears from a motor 90. (Figs. 9, 10, and 11.) The motor shaft drives a gear shaft SI and, through the speed translating or reducing gears 92, mounted thereon, the gear shaft 94 having a gear 95 located in meshing relation with a suitable ring gear 91 secured on the rotor. The shaft 9|, also, operates a pair of timer 98, by gears I intermeshing with a gear IOI on the shaft 8|. The ratios of the interrelated gears 82, 95, 81, I00, and IN are such that the shafts of the timers 88 complete one revolution as the rotor 85 moves in sequential registration from port to port. The timers provide the requisite time period of the weld, its extent being predeterminable upon the setting and length of the cams I02.

The timers may partake of any conventional construction, each having a usual form of circuit closer switch I08 adapted to be closed and opened by a cam I02, the initial moment of the opened and closed periods of each switch being adjustable by shifting of the timer case. The circuit closer switches I03 are connected in series with the coil I04 of a magnetic relay I05, which completes the circuit of the primary I06 of the transformer I01 through the switch I08 to the main switch I09 and the supply lines I I0. Through the use of two circuit closers, the timing of the oper ations of the circuit closers may be adjusted in relation to each other to vary the energized period of the relay I05 and, accordingly, the period for the flow of the welding current through the switches 48.

When it is found necessary to adjust the timing of the period of the weld, as controlled by the cams I02 and circuit closers I03, the circuit closers may be arcuately moved, with reference to the cams, to alter their position and their opening and closing movements. (Figs. 8 and 11.) Each of the casings III of the timers 88 are provided with a plate .II2, having a finger portion extending therefrom. Each circuit closer I03 is mounted within the casing III and is operated by a cam I02. Each plate II2 may be adjusted relative to its associated cam and secured against movement, by a bolt II3, located in a slotted portion of the plate. Thus, the initiation or completion of the weld period may be controlled by the positioning of either of the circuit closers I03, since the switches are connected in series in the circuit of the relay I05 and will open or close the circuit, according to the predetermined positions of the circuit closers and the depressed portions II8 of the cams I02. The circuit for the coil I04 of the relay I05, upon closure of the circuit closers I03, is completed through the switch II4 to the supply lines I I5.

In order to adapt the controlling circuits to any character of work and to obtain a maximum amount of efliciency, both in the operation and welds produced, means is provided herein for adjusting the interval of the pressure period by the speed of the motor 80, adjusting the potential of the welding current emanating from the transformer I01 to the primary II6 of the welding transformer 28 and, the period of flow, by means of the circuit closers I03. The interrelation of these facilities and their utilization produces a welding control medium whereby metals of various thicknesses may be welded during a single operation without interruption of the welding cycle or production of improperly formed welds in areas of increased resistance to the flow of welding current.

Where it is found advantageous to protect the electrode I8, as well as the surface of the metal, by affording periods of momentary cessation of the flow of welding current when a period of weld is necessarily lengthened, means may, also, be provided, whereby the pneumatically created impulse of contact in the switch 48 may be repetitively applied and the related electrode I8 will, thus, carry the flow of welding current a number of times in sequence, the recurrence of the flow of the welding current being spaced by intervals to enable cooling of. the electrode engaged thereby.

To carry out the above described features of my invention, a drum II! is mounted on the bored stem 88 of the rotor 85. The annular exterior surface of the drum has formed therein a plurality of grooves H8, in which arcuate cams I20 may be positioned. The cams I20 are of such lengths as maybe determined to produce required periods of control and are so located with reference to the movement of the rotor 85 as to actuate controlling devices when a port 83 of the rotor registers with the passageway 82, identified with the pipe conduit of the switch 48 and electrode I8 to be controlled. Thus, when it is found desirable to diminish the speed of the motor 80, the cams I20 may be adapted to actuate suitable valves, which are included in the pneumatic system of the machine.

For convenience of assembly, the casing has a supporting wall portion I2I, upon which a pair of brackets I22 are secured. The brackets I22 support a chambered valve casing I23 and a plurality of switches I24. The valve casing I23, a detail of which is illustrated in cross-section in Figs. 5 and 6, is connected, at one end thereof, to an air supply pipe I25, by a conduit I21, and, at itsv opposite end, to the air motor 90, by a conduit I28. (Figs. and 11.) The air supply enters the casing I23 and flows through the passageway I30. Valves I33 are located at regular intervals within the passageway I30. The valves are provided with chambers I3I, which are connected to the passageway I30, upon actuation of the valve members. The chamfered orifice of each valve I33 is closed by a springloaded plunger I32, which seats in the orifice and is removed therefrom by a pin I34. The pin has an outwardly extended portion, which is positioned in the path of certain of the cams I20 on the drum II1. Each of' the valve chambers I3I communicates, through a metered port, with a passageway I35 connected to the motor 80 by the conduit I28. The effective area of the metering port is determined by a needle valve I31,

which may be designed for ready adjustment, at a point external to the valve casing I23. Preferably, the needle valves I31 are adjusted, with respect to each other, to graduate the speed of the air motor 90 upon regular and graduated enlargement of. the metered ports connecting the chambers I3I with the passageway I35.

As diagrammatically illustrated in Fig. 11 of the drawings, the valves I33 are connected to the source of supply of air pressure I38 by the conduits I21 and passageways I30. The valves and their actuating pins I34 are spaced within the valve casing I23 to locate the pins in positions of actuation by cams I20 supported in the alternate grooves II8 of the drum II1. As shown in detail in Figs. 5 and 10, the leading, chamfered end of one cam extends over the rear or 101- lowing end of a preceding cam so that the variance in motor speed may be accomplished without interruption to the continuance of the opertion of the motor. The cams I40, located in the grooves II8 inter mediate the grooves wherein the cams I20 are secured, engage pins MI in actuating relation to operate the switches I24. The switches I24 are located, on a bracket similar to the bracket I22, diametrically opposite the valve casing I23, in relation to the drum II1. (Figs. 10 and 11.) The switches, normally biased to an open position, are connected by a line I42 to one side of the primary II8 of the welding transformer 28. suitable connection of the other side of the primary being made to one side of the secondary I45 of the transformer I01. The switches I24 complete the circuit from the line I42 and one side of the primary II5 to various taps made in the winding of the secondary I45. The potential of the electric current flowing from the secondary I45 of the transformer I01 will, thus, be varied according to the location of the actuating cams I40. The cams have a length, substantially the same as the cams I20 and, preferably, are located with respect to the cams I20, associated therewith, to reduce or increase the potential of the electric current flowing to the primary H6, simultaneously, with any modification in the speed of the air motor 80. The cams I20 and I40 may, therefore, be arranged in groups or pairs of associated grooves H8 in the drum to produce the desired controbof their respective systems. The cams I20 and I40 are, also, located with reference to the sequential registration of the ports of the rotor 85 with the passageways 82, so that the particular welders associated therewith perform, through their switches and electrodes, their required operations.

In one embodiment of my invention, and as illustrated in the drawings explanatory thereof, the cams I20 and I40 are 50 located on the drum I I1 that one working cycle of an operated welder electrode unit will transpire during a portion of one revolution of the drum. The drum and the casing may be adapted to initiate and/or control a plurality of work cycles, in repetition or separately. The passageway 81, extending diametrically through the rotor to connect the outlet ports 83 with the source of supply of pneumatic pressure, thus, furnishes such pressure for an inactive period to one of the ports of the rotor until the port approaches registration with the passageway 82 connected to one of-the pneumatically-operated switches 48. Also,'traversal of one of the outlet ports 83 of the rotor and consequent registration with plugged ports in the casing 80 will produce a reactant pressure on the opposite outlet port to effect a satisfactory seal as it comes into registration with a passageway 82 connected to oneof the pipe conduits 84.

Where a suitable controlling period has been established by the lengths and location of the cams I20 and I40 on the drum H1, a further increase in metal thickness may require a variance in the setting thus afforded, or the heat producible by an extended period of the weld may require such a variance to prevent overheating of the metal or the electrode tip. The switch 48, associated with the electrode I8 abutting the surface of a part of the work having a greatly increased thickness, may, thus, be connected to a multiple accumulator valve' I50 (Figs. 4 and '1), whereby the desired mode of control by the cams may be maintained, yet any one of the switches 48 may be connected to a plurality of passageways 82 to be actuated thereby. The casing I5I of the valve I50 is provided with a chamber I52, the ends of which terminate in threaded outlets I54 and I55. The chamber I52 is connected to a chamber I51 by a plurality of passageways I58, the axes of the chambers I52 and 151 being in substantially parallel relation. Opening into the chamber I52 is a pair of laterally extending passageways I58 connecting the chamber with a threaded outlet I80. The outlets I54, I55, and I60 may be connected by certain of the pipe conduits 84 to the casing 80 so that, upon registration of the port 83 of the rotor 85 with the passageways 82 associated therewith, pneumatic pressure will be introduced into the chamber I52 and through one of the passageways I58 to the chamber I51. The chamber I51 is connected to the designated switch 48 by a pipe conduit I5I. In order to prevent escape of the pressure from its intendedcourse, through any of the other outlets, since the conduits 84 connected thereto will then be opened to the atmosphere, the chamber I52 has located therein a pair of plungers I52. The plungers have beveled or chamfered ends and are of such suitable length that their contiguous faces abut each other in the vicinity of the openings of the laterally extending passageways I58. As positioned 'in Figs. 4 and '1, the plungers I82 have been the chamber I52.

2,287,945 subsequent registration of one of the ports of the rotor 85 with the passageways 82 connected to the valve I50 by the conduits 84, the plungers will be moved to expose one and then the other of the passageways I58, which are covered and closed by said plungers. When the pneumatic pressure is directed to either of the laterally extending passageways I58 from the outlet I80, it will cause separation of the plungers at the point of their abutment and closure of the passageways I58, located most proximate the ends of Where it may be found advantageous, the chamber I51 may be provided with a plurality of, threaded outlets for connection to a series of switches 48, whereby theaccumulative action afforded by the valve I50 may efiect a series of switches to repeat closure of the welding circuit.

As diagrammatically illustrated in Fig. 11, the right-hand switch 48 is under pressure to indicate the flow of welding current therethrough to its related electrode. Upon movement of the rotor 85, in a clockwise direction, the next passageway 82 will be connected, by a conduit 84, to the multiple valve I50 and, through the pipe conduit IGI, to the left-hand switch 48. Thereafter, the next succeeding passageways 82 will be put in conduit connection with the valve I50. Thus, metal located beneath the associated electrode will be, periodically, connected to the secondary 21 of the transformer 28, the periods of connection being interrupted by movement of the rotor to allow cooling of the electrode and the metal. Also, as shown in Fig. 11, it will be noted that the pins I34.and I4I, operating their associated valve I23 and switch I24, respectively, and actuated by the cams I20 and I40, respec-- tively, in the uppermost pairs of grooves II8, are approaching the ends of their cams and during the interval of their controlled engagement, the speed of the pneumatically-operated motor 90 has been controlled by the related valve chamber I3I to operate the rotor 85 and circuit closers I 03 at the predetermined rate for ordinary operation. The switch I24, actuated by the pin I, is connected by a line I54 to the end of the secondary I45 of the transformer I06 to produce a current flow of high potential to the primary II8 of the welding transformer through the line I42, the switch I24, and the line I64, from the secondary I45.

Progressive movement of the drum II1 will efiect engagement of the lowermost cams I20 and I40 with their associated pins I34 and I, respectively, and actuation of the related valve I38 and switch I24. The speed of the motor 80 will, thereupon, be materially increased as the communications from the source of supply of pneumatic pressure to the motor are amplified. The circuit of the secondary will, also, be varied upon closure of the switch I24. The switch is connected to the innermost tap of the secondary I45 by a line I65 and through the switch I24 and line I42 to reduce the potential of the current flowing to the secondary II6 of the weldingtrans'former 28. The modification of control in both the pneumatic and electrical systems will, accordingly, produce, between the weld periods, a shorter interval of the weld periods and a lower potential for the welding current during the actuation of the valve and switch associated with the cams in the lowermost pair of grooves II8, and/or during the direction of the pneumatic pressure through the multiple valve I 50.

To afford further modifications and adjustments for the operation of the welding elements, cams may be located in other of the pairs of grooves II8. Upon movement of the rotor 85 to the succeeding passageways 82 in the casing 80, the controls for the motor and the transformer I01 will, thus, be dependent upon the arrangement of the cams and the actuation of the valves I 33 and switches I24, as may be predetermined. When the rotor completes, substantially, one-half of its revolution, a welding cycle may, if desired, be accomplished, depending upon the number of welder electrodes I8 and the associated switches 48 connected to the passageways 82 of the casing 80. The operation of the motor may then be halted and the frame 20 elevated for removal of the work.

While the hereinabove description has'been made with reference and in relation to any grouping of welder electrodes, provision is made, as an illustrative embodiment of my invention, for a modified grouping of electrodes when operating circumstances will permit. As shown in Figs. 1 and 2, welder electrodes maybe mounted in a U-bar I10 and connected by similar flexible conductors of uniform length to related switches 48 supported on the panel 55. The U-bar I10 is a part of a reciprocating frame I1I, which is pivotally supported on the carrier frame 20. The U-bar is caused to aline the electrodes with the work, positioned at, substantially, right angles to the work on the projections 22 of the bar 24. The bar 24 may be provided with similar electrodes I 12 for engaging such angularly positioned work or angularly bent portions of work; that work having substantially an L-shape. Actuation of the U-bar I10, to move the electrodes into engaging position, may be aflorded by a pair of double-action cylinders I14, which are connected to the source of pneumatic pressure I38 by suitable valves, and'their piston rods I15 may be connected to the frames 20 and HI by the links I18. The switches 48 may be connected, by conduits, to passageways in the casing 80 to produce, in sequential order, a flow of welding current through the electrodes, upon completion of the operation of the group of welder electrodes, as previously described, and during the traversal of the portions I80 and I8I of the uppermost cams I20 and I40, relative to the associated valve I33 and switch I24, to complete, substantially, the remainder of half revolution of the drum H1 and the rotor 85.

If desired, and in keeping with common practice,-passageways may be provided in the various actuated switch casings 58 and blocks 29, and interconnected by tubing I85-to convey a continuous flow of coolant for removing the heat induced by the operation of the welders.

I claim:

1. In a welding machine, a plurality of welders having welding electrodes for engaging the work; a source of welding current; a plurality of fluid operated switches for connecting the electrodes to the source of welding current; a source of supply of fluid pressure; means for connecting the switches to the source or fluid pressure in succession; a fluid pressure motor connectable to the source for operating the said means; a valve for controlling the speed of the motor; and an riod in which certain of the electrodes is 0011- I nected to the source of current.

2. In a welding machine, a plurality of welders having welding electrodes for engaging the work; a source of welding current; a plurality of fluid operated switches for connecting the electrodes to the source of welding current; a source of supply of fluid pressure; rotative means for connecting the switches to the source of fluid pressure in succession; a fluid pressure motor connectable to the source for operating the said rotative means; a valve for controlling the speed of the motor; an element connected to the said rotative means for periodically operating the valve to vary the speed of movement of the element and the length of period in which certain of the electrodes is connected to the source of current; and electric means for selectively varying the current quantity that flows through each electrode according to the work to be done by the electrode.

3. In a welding machine, a plurality of welders having electrodes for engaging the work; a source of supply of welding current; a source oi. fluid pressure; a plurality of fluid operated switches for connecting the source of current with the electrodes; a plurality of pressure pipes; a means having a movable member for connecting the said source of fluid pressure to the switches in succession through the said pressure pipes; a valve for controlling the fluid pressure from the said means through certain of said pipes and having a movable valve member operated by the pressure in said certain of said pipes; and an outlet pressure pipe connected to the valve and to a switch to produce repetitive operations of the switch.

4. In a welding machine, a plurality ofwelders having electrodes for engaging the work; a source of supply of welding current; a source of fluid pressure; a plurality of fluid operated switches for connecting the source of current with the electrodes; a plurality of pressure pipes connected to the said source of fluid pressure; a means having a movable member for connecting the switches in succession with the said pressure pipes; a valve for controlling the fluid pressure from the said means through certain of the said pipes and members operated by the pressures in said certain pipes; and a pipe connecting the valve and a switch to produce repetitive operations of the switch.

5. In a welding machine, a plurality of welders having electrodes for engaging the work; a source of supply of welding current; a source of fluid pressure; a plurality of fluid operated switches for connecting the source of current with the electrodes; a plurality of pressure pipes; a means having a movable member for connecting the said source of fluid pressure to the switches in succession through the said pressure pipes; a valve for controlling the fluid pressure from the said means through certain of said having a plurality of movable valve pipes and having a movable valve member operated by the pressure in said certain of said pipes; an outlet pressure pipe connected to the valve and to a switch to produce operations of the switch; a fluid pressure motor connectable to the source for operating the said means; a valve for controlling the speed of the motor; and an element connected to the said means for periodically operating the valve to vary the speed of movement of the element and the length of period in which certain of the electrodes is connected to the source of current.

6. In a welding machine, a plurality of welders having electrodes for engaging the work; a source of supply of welding current; a source of fluid pressure; a plurality of fluid operated switches for connecting the source of current with the electrodes; a plurality of pressure pipes; a means having a movable member for connecting the said source of fluid pressure to the switches in succession through the said pressure pipes; a valve for controlling the fluid pressure from the said means through certain of said pressure pipes and having a movable valve member operated by the pressure in said certain of said pipes; an outlet pressure pipe connected to the valve and to a switch to produce operations of the switch; and an electric means for varying the current quantity; and means for connecting certain of the electrodeswith said electric means during the connection through the said switches associated with the said certain of the electrodes.

7. In a welding machine, a source of fluid pressure; a fluid pressure motor connected to the said source; a rotor operated by the motor; a plurality of restriction valves for restricting the flow of fluid under pressure to the motor to vary the speed of the motor; a source of supply of electric current; a variable transformer connected to the source of supply of electric current and having current regulative potential terminals; a plurality of welders, each welder having an electrode for engaging the work; a plurality of fluid operated switches for completing the connections of the variable transformer to the electrodes; a plurality of electric switches; and the rotor having a rotatable connector for connecting the .said switches in succession to thesource of fluid pressure, and having rotatable members to complete the connection of the operated switch to its associated electrode with a selected voltage terminal and for operating the restriction valves to vary the period of flow through the electrodes and the work.

8. In a welding machine, a plurality of welders having welding electrodes for engaging the work; means for moving the welders and simultaneously pressing the electrodes against the work with a welding pressure; a source of welding current; a plurality of fluid operated switches, a switch associated with each electrode for connecting its associated electrode to the source of welding current; a source of fluid pressure; a

step-by-step means for connecting the switches to the source of fluid pressure in succession; and an electric means including a plurality of switches operated by the step-by-step means for selectively varying the current quantity that flows through each electrode and its associated switch as it is sequentially connected to the source of welding current according to the work to be done by the electrode.

HUGO PURAT. 

